1. Field of the Invention
This invention relates in general to communication systems, and more particularly, to a method and apparatus for managing information communicated over a network.
2. Description of Related Art
The state of communications technology, particularly that which affects the Internet, is currently in flux and subject to rapid and often uncoordinated growth. The ubiquity and diversity of personal computers and set-top boxes has placed significant pressure on the providers of communications system infrastructure to accommodate the alarming increase in the number of new users that demand immediate access to Internet and other network resources. The rapid development of new and sophisticated software made available to users of such services places additional demands on system infrastructure.
Conducting commerce over the Internet and other networks is a practice that is gaining acceptance and popularity. By way of example, traditional on-line services, such as those offered by Internet providers, typical charge customers a monthly fee for access to basic services and resources, such as proprietary and public databases of information. Such traditional service providers also advertise any number of products or services which are purchasable on-line by the user.
Other forms of Internet commercialization currently being considered or implemented include offering of video and audio conferencing services, and a variety of other real-time and non-real-time services. The providers of these services, as well as the providers of communications system infrastructure, are currently facing a number of complex issues, including management of network capacity, load, and traffic to support real-time, non-real-time, and high-bandwidth services, and implementing a viable billing scheme that accounts for the use of such services.
The communications industry is expending considerable attention and investment on one particular technology, referred to as asynchronous transfer mode (ATM), as a possible solution to current and anticipated infrastructure limitations. Those skilled in the art understand ATM to constitute a communications networking concept that, in theory, addresses many of the aforementioned concerns, such as by providing a capability to manage increases in network load, supporting both real-time and non-real-time applications, and offering, in certain circumstances, a guaranteed level of service quality.
Although the current ATM service architecture would appear to provide, at least at a conceptual level, viable solutions to the many problems facing the communications industry, ATM, as currently defined, requires implementation of a complex traffic management scheme in order meet the objectives articulated in the various ATM specifications and recommendations currently being considered. In order to effectively manage traffic flow in a network, conventional ATM traffic management schemes must assess a prodigious number of traffic condition indicators, including service class parameters, traffic parameters, quality of service parameters and the like. A non-exhaustive listing of such parameters and other ATM traffic management considerations is provided in ITU-T Recommendation 1.371, entitled Traffic Control and Congestion Control in B-ISDN, and in Traffic Management Specification, version 4.0 (af-tm-0056.000, April 1996), published by the Technical Committee of the ATM Forum.
Notwithstanding the complexity of conventional ATM traffic management schemes, current ATM specifications and recommendations fail to adequately address the need of service providers for a methodology that provides for accurate and reliable charging of services utilized by user""s of the network. Even if one were to assume that a charging scheme that accounts for most or all of the currently defined ATM traffic management properties could be developed, such a scheme would necessarily be complex and would typically require administration by highly skilled operators. The high overhead and maintenance costs to support such a billing scheme would likely be passed on to the network provider and, ultimately, to the network user.
Some commentators have suggested that a solution to these problems may be found by increasing the bandwidth or capacity of the network (e.g., the Internet). Implementing this overly simplistic solution would require an appreciable investment of hardware, software, and, most likely, replacing existing communication lines with high bandwidth transmission lines, such as fiber optic lines. This suggested solution, however, would likely result in undisciplined network expansion and uncoordinated management of network traffic. Also, such a solution, if implemented, would appear to obviate the need for much of the sophisticated traffic management features currently defined in ATM specifications.
Accordingly, there is a need in the communications industry for a network management architecture and method that is simple in concept and in its implementation, yet adequately addresses the quality of service requirements to support a variety of network services, including real-time and non-real-time services. There exists a further need for a system and methodology that provides for the implementation of a simple and effective charging capability that accounts for the use of network services. The present invention fulfills these and other needs which remain unaddressed by prior art traffic management approaches.
The basic objectives of future Internet are to increase the network capacity, to offer a practical real-time service, and to develop a feasible charging scheme. These objectives introduce very strict requirements for the traffic control system. A Simple Integrated Media Access (SIMA) is recently introduced to present a new simple approach for traffic management. According to the SIMA concept, each customer shall define only two issues before a connection establishment: a nominal bit rate (NBR) and a selection between real-time and non-real-time service classes. NBR forms the basis of charging, and it defines how the network capacity is divided among different connections during overload situations. Simplicity of SIMA means that, on one hand, the network operator does not guarantee the continuous availability of nominal bit rate, and on the other hand, the user is allowed to send data with any bit rate independently of the NBR. As a result, the strength of SIMA lies in its wide area of applications. Accordingly, there is no need to build complex systems with several service classes each appropriate to only certain applications.
Generally, there are two main alternatives for the realization of the SIMA service: the first one based purely on packet network, and the second one based on the use of ATM for the switching and transportation. As the basic implementation of these two alternatives does not considerably differ from each other. The main difference is that the ATM makes possible to realize more easily a satisfactory real-time service. The implementation of the SIMA service includes two main parts: access nodes (A) and core network nodes (C) presented in FIG. 1. The traffic measurement of every flow of the network is performed at access nodes (A), whereas at the core network nodes (C), the traffic control functions do not need to know anything about the properties of separate flows. As shown in FIG. 1, one customer equipment (CE) is connected to another customer equipment (CE) through a SIMA network with access nodes (A).
When a network operator offers a SIMA service, a customer first pays for some Nominal Bit Rate (NBR, e.g. kbit/s) and then the customer can trade the speed for Quality of Service (QoS) for the transmission of its data packet. Specifically, the SIMA network, once receiving customer""s NBR, measures actual bit rate of selected connection and determines a priority level (PL) of each data packet at the user/network interface (UTNI). Thereafter, the data packet is transmitted to the SIMA network (from an access node to a core network node) whereby the SIMA network determines the state of buffer(s) of the core network node so as to decide whether the core network node should accept or discard packet based on PL of the data packet and the state of buffer(s).
One principle of a SIMA network is that data packets are discarded only when necessary and not automatically on the network interface. The discarding decision is mainly based on two considerations: 1) the priority of the data packet; and 2) the allowed priority level (PL) in the buffer(s) of the particular core network node.
One of the concerns for the existing SIMA networks is that if the allowed priority level in the buffer(s) varies through the network at a certain moment, some data packets may be delivered through several network nodes, but then discarded near the end of the data packet transmitting path. This kind of behavior is not desired as it can significantly waste network resources.
Therefore, it can be seen that there is a need for a SIMA network to be equipped with a routing system that is able to equalize or substantially equalize the allowed priority levels as much as possible, or in other words, to transmit data packets in such a path that the probability of being discarded is the least.
It can also be seen that there is a need for a method and system for managing information communicated over a network, especially a SIMA network, as well as enhancing the ability of increasing the network capacity, offering a practical real-time service, and developing a feasible charging scheme.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention is directed to a system and method for communicating elements of information over a network, and more particularly, to a system and method for managing information communicated over the network. The network includes access nodes which provide a user access to core network nodes. Each access node or core network node has a buffer with an allowed priority level for data transmission. Each node in network monitors the allowed priority level of every outgoing link. The monitoring device gives the routing device information about the allowed priority level. Each node delivers the information about the current allowed priority level of every link to all other nodes. The first node determines the total costs for all reasonable routes to the target node. The determination takes into account the allowed priority levels and/or the length of the data path or route. The route with the lowest total cost is selected. The selected route has the least probability for the data to be discarded among all the routes. Accordingly, the present invention makes possible the equalization of priority levels in SIMA network, as it preferably routes packets to those links that have the lowest allowed priority level.
The present invention provides a routing system for a SIMA network for transmitting packets of information. In one embodiment, the present invention includes: a first network node transmitting the packets of information; a second network node for receiving the packets of information transmitted from the first network node; at least two routes connected between the first and second network nodes, at least one of the routes having a third network node, the third network node having at least one outgoing link; and the first network node comprising: at least one outgoing link, the outgoing link being a part of one of the two routes; a route controller for transmitting the packets of information from the first network note to the second network node; a buffer, the buffer storing the packets of information and an allowed priority level for each of the outgoing links of the first and third network nodes, the packets of information being transmitted via one of the routes selected by the route controller; a monitor, the monitor coupled to the buffer and the route controller, the monitor monitoring the allowed priority level of each of the outgoing links of at least the first network node and informing at least the first and third nodes the allowed priority level of each of the outgoing links; and wherein the route controller selects one of the routes from the first network node to the second network node, based on the allowed priority levels of the outgoing links of at least the first and third network nodes.
One aspect of the embodiment is that the route controller selects one of the routes with a lowest cost determined by the allowed priority levels of at least the first and third network nodes.
In an alternative embodiment, the present invention includes: a first network node transmitting the packets of information; a second network node for receiving the packets of information transmitted from the first network node; and the first network node comprising: at least two outgoing links for transmitting the packets of information to the second network node, and each of the outgoing links having a predetermined preference value; a buffer, the buffer storing the packets of information and having an allowed priority level for each of the outgoing links, the packets of information being transmitted via one of the outgoing links selected by the route controller; and wherein the route controller selects one of the outgoing links based on the allowed priority level and the predetermined preference value of each of the outgoing links.
One aspect of the alternative embodiment is that the route controller determines a value difference between the allowed priority level and the predetermined preference value of each of the outgoing links and selects one of the outgoing links which has the largest value difference.
The present invention also provides a method of routing packets of information in a SIMA network from a first network node to a second network node, comprising the steps of: providing at least two routes connected between the first and second network nodes, at least one of the routes having a third network node, the first and third network nodes each having at least one outgoing link; monitoring an allowed priority level of at least the one outgoing link of the first network node, at least the one outgoing links being a part of the routes; informing the first and third network nodes the allowed priority level of each of the outgoing links; and selecting one of the routes from the first network node to the second network node based on the allowed priority levels of the outgoing links of at least the first and third network nodes.
One aspect of the method is that the selecting step selects one of the routes with a lowest cost determined by the allowed priority levels of at least the first and third network nodes.
The present invention further provides an alternative method of routing packets of information in a SIMA network from a first network node to a second network node, comprising the steps of: providing at least two outgoing links for the first network node, and each of the outgoing links having a predetermined preference value; monitoring an allowed priority level of each of outgoing links; and selecting one of the outgoing links to transmit the packets of information from the first network node to the second network node based on the allowed priority levels and the predetermined preference value of the outgoing links.
One aspect of the alternative method is that the selecting step includes determining a value difference between the allowed priority level and the predetermined preference value of each of the outgoing links, and selecting one of the routes which has the biggest value difference.
One of the basic ideas of the present invention is to use information of the allowed priority levels at network nodes for data packet routing.
Other embodiments of a system in accordance with the principles of the invention may include alternative or optional additional aspects. One such aspect of the present invention is that other appropriate selecting methods can be used to determine which route should be taken It will be appreciated that other equivalent alternative embodiments of can be used without departure of the present invention.